1. Field of the Invention
The present invention relates generally to thermal management devices for electronic devices and more specifically it relates to a spray cooling system for extreme environments for providing an isolated environment for electronic devices regardless of external environmental conditions.
2. Description of the Related Art
Thermal management systems for electronic systems have been in use for years. In order to maintain maximum performance from electronic components, the components need to be maintained within a relatively narrow temperature band. Thermal management systems are utilized to maintain this desired narrow temperature band.
In environments where extreme temperatures are present (e.g. −65° C., +70° C., etc.), it is critical to provide a thermal management system that provides a desired internal operating environment to maintain peak efficiency, power and prevent system failure. In addition, some external environments include hostile elements such as but not limited to dust, sand, debris, salt, water, fog, condensed water vapor, contaminants and the like, which require the complete isolation of electronic components from the harsh external environment. Extreme external environments are encountered within various applications such as aircraft, ships, ground based applications and the like. It is absolutely crucial that electronic components be maintained in a safe internally controlled environment when in extreme external environments.
Conventional thermal management systems commonly utilized today are comprised of air-cooled enclosures (forced flow or free flow), conduction cooling and liquid immersion cooling. The main problem with air-cooled enclosures is that they introduce harmful external elements into the electronics enclosure. Another problem with air-cooled enclosures is that they do not provide a method to increase the temperature of electronic components to a desired operating temperature when the external temperature is extremely low (e.g. −65° C.).
Problems with conduction cooling systems include increased weight, increased size, increased mass, expensive, reduced shock and vibration tolerance, and reduced electronic component performance. A significant design limitation with conduction cooling systems is that they must be in direct contact with the electronic components which limits flexibility and increases expense. The large mass also increases the amount of time required to increase the temperature of electronic components to a desired operating temperature.
Spray cooling technologies are being adopted today as the most efficient option for thermally managing electronic systems in an enclosed internal environment. Spray cooling utilizes an atomized dielectric spray that is applied directly to the electronic device thereby forming a thin film on the electronic device. Spray cooling may be performed locally (i.e. where the chip is sprayed directly) or globally (i.e. where the chip and surrounding electronics/boards are also sprayed). U.S. Pat. No. 5,220,804 entitled High Heat Flux Evaporative Spray Cooling to Tilton et al. describes the earlier versions of spray cooling technology. U.S. Pat. No. 6,108,201 entitled Fluid Control Apparatus and Method for Spray Cooling to Tilton et al. also describes the usage of spray cooling technology to cool a printed circuit board.
While the conventional thermal management systems may be suitable for the particular purpose to which they address, they are not as suitable for providing an enclosed unit that maintains a desirable internal temperature over an extreme external temperature range. Conventional air-cooled technologies do not protect the electronic components from contamination by harmful elements. Conventional conduction cooling technologies are expensive and bulky.
In these respects, the spray cooling system for extreme environments according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of providing an enclosed unit that maintains a desirable internal temperature over an extreme external temperature range.